The invention relates to coating compositions, particularly for topcoats or coatings forming the outermost layer of composite coatings.
Clearcoat-basecoat composite coatings are widely used in the coatings art and are notable for desirable gloss, depth of color, distinctness of image and/or special metallic effects. Composite systems are particularly utilized by the automotive industry to achieve advantageous visual effects, especially a high degree of clarity. However, a high degree of clarity in the clearcoat makes it easier to observe defects.
Silicon-containing materials have been introduced into coating compositions to increase the resistance of coatings to surface scratching and marring. A coating layer with silicon-containing materials may have poor adhesion with subsequently applied coating layers, however, due to the low surface tension produced by the silicon atoms. Generally, when the silicon-containing materials are added to the outer coating layer for scratch and mar resistance it is contemplated that no further coating layer will be applied over this outer coating layer. It sometimes becomes necessary to apply a further layer, however, such as when a defect in the outer coating must be repaired by applying a repair coating layer. A successful repair requires good adhesion of the repair coating layer to the underlying coating layer, which may be compromised when the underlying coating layer includes silicon-containing materials. Extra steps must then be taken to assure good adhesion of the repair coat, for example sanding and cleaning the underlying coating before applying the repair coating layer.